Washing machine and control method thereof

ABSTRACT

A washing machine and a control method thereof in which laundry is washed in a state of being directly heated by steam. The washing machine includes a microcomputer for controlling the overall operation of the washing machine to wash laundry by using steam. The microcomputer controls operations of wetting laundry with a small amount of water prior to generation of steam, uniformly spraying detergent over the wet laundry, and injecting steam onto the laundry. Accordingly, it is possible to achieve a reduction in the amount of water to be used and a reduction in wash time while preventing the laundry from being stained or damaged during the wash operation using steam.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.2004-680, filed on Jan. 6, 2004, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Apparatuses and methods consistent with the present invention relate toa washing machine and a control method thereof, and more particularly,to a washing machine and a control method thereof in which laundry iswashed while being directly heated by steam.

2. Description of the Related Art

There are conventional washing machines using wash water heated by aheater installed in a water tub. In such a washing machine, a detergentis put into a water tub during the supply of a predetermined amount ofwater. As the water tub is rotated in forward and reverse directions ina repeated fashion, the detergent is dissolved in the water suppliedinto the water tub. Thus, a wash process is carried out, using thedetergent solution.

In order to effectively dissolve a detergent in water, and to transferthe resultant detergent solution over all portions of the laundry to bewashed, it is necessary to use an increased amount of wash water.However, such an increase in the amount of wash water to be used causesan increase in the heating time of a heater adapted to heat the washwater. As a result, an increased consumption of electric energy and anincrease in wash time occur.

In the above case, there is also a drawback in that the time taken forthe wash water to reach a predetermined high temperature for aneffective wash is prolonged.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above mentionedproblems, and an aspect of the invention is to provide a washing machineand a control method thereof in which laundry is washed in a state ofbeing heated by steam, so that it is possible to reduce the wash timewhile using a reduced amount of water.

Another aspect of the invention is to provide a washing machine and acontrol method thereof which are capable of preventing laundry frombeing stained or damaged by hot steam as the steam comes into contactwith the laundry to heat the laundry, while achieving an enhancement inwashing.

In accordance with one aspect, the present invention provides a washingmachine comprising: a rotating drum for containing laundry; a drumdriving unit for driving the rotating drum; a steam generator forgenerating steam and supplying the steam into the rotating drum; and acontroller for controlling operations of injecting the steam suppliedfrom the steam generator into the rotating drum to heat the laundry intoheated laundry, and washing the heated laundry.

The washing machine may further comprise a water supply unit forsupplying water into the rotating drum. In this case, the controller maydrive the water supply unit to wet the laundry with water into wetlaundry before the operation of washing the heated laundry.

The controller may control the drum driving unit to rotate the rotatingdrum in forward and reverse directions in an alternating fashion whilethe laundry is wetted by the water.

The washing machine may further comprise a detergent dissolving unit forsupplying a detergent solution into the rotating drum. In this case, thecontroller may drive the detergent dissolving unit to spray thedetergent solution over the wet laundry.

The controller may control the drum driving unit to rotate the rotatingdrum at a predetermined speed before the detergent solution is sprayed.

The predetermined speed may be a speed sufficient to bring the laundryinto constant contact with an inner peripheral surface of the rotatingdrum while defining an empty space at a central interior of the rotatingdrum.

The controller may control the detergent dissolving unit to spray thedetergent solution when a rotating speed of the drum corresponds to thepredetermined speed, and control the drum driving unit to reduce therotating speed of the rotating drum while the detergent solution isbeing sprayed.

The controller may control the drum driving unit to rotate the rotatingdrum in forward and reverse directions in an alternating fashion so thatthe detergent solution sprayed over the laundry is transferred over allportions of the laundry.

The steam generator may comprise a heating tank for containing water,and a heater installed in the heating tank, and adapted to heat thewater in the heating tank, thereby generating steam. The heater may becontrolled by the controller.

The steam generator may further comprise a water level sensor forsensing a water level in the steam generator, and a water temperaturesensor for sensing a water temperature in the steam generator. The waterlevel sensor and water temperature sensor may provide, to thecontroller, information about the water level and water temperaturesensed thereby.

The steam generator may further comprise a steam supply valve installedat an outlet of the heating tank. In this case, the controller may openthe steam supply valve to supply the steam generated from the heatingtank.

In accordance with another aspect, the present invention provides acontrol method for a washing machine comprising the steps of: when asetting of a user corresponds to a wash course for washing laundry byusing steam, supplying water into a rotating drum, and wetting laundrycontained in the rotating drum into wet laundry with the supplied water;spraying a detergent solution over the wet laundry; generating steam bya steam generator; injecting the generated steam into the rotating drum,thereby heating the laundry as heated laundry; and washing the heatedlaundry.

The rotating drum may be rotated in forward and reverse directions in analternating fashion while the laundry is wetted by the water.

The rotating drum may be rotated at a predetermined speed to define anempty space at a central interior of the rotating drum.

The detergent solution may be sprayed in the empty space defined in therotating drum, and the rotating speed of the rotating drum is reducedbelow the predetermined speed while the detergent solution is beingsprayed.

The rotating drum may be rotated in forward and reverse directions in analternating fashion for a predetermined time after completion of thespray of the detergent solution.

The predetermined time may span from a point of time when the rotatingdrum is stopped to a point of time just before the generated steam isinjected into the rotating drum.

BRIEF DESCRIPTION OF THE DRAWINGS

The above aspects, and other features and advantages of the presentinvention will become more apparent after reading the following detaileddescription when taken in conjunction with the drawings, in which:

FIG. 1 is a schematic perspective view illustrating the configuration ofa washing machine according to an embodiment of the present invention;

FIG. 2 is a block diagram illustrating a control configuration appliedto the washing machine according to the illustrated embodiment of thepresent invention;

FIG. 3 is a flow chart illustrating a method for controlling the washingmachine in accordance with an embodiment of the present invention; and

FIGS. 4A and 4B are schematic views for explaining a wash cycle carriedout by using steam in the washing machine in accordance with the controlmethod, respectively.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Exemplary embodiments of the present invention will now be described indetail with reference to the annexed drawings.

FIG. 1 is a schematic perspective view illustrating the configuration ofa washing machine according to an embodiment of the present invention.This embodiment is applied to a drum type washing machine equipped witha steam generator.

As shown in FIG. 1, the drum type washing machine according to theillustrated embodiment of the present invention includes a first watersupply pipe 12 for supplying water introduced from an external waterservice pipe 2 to a water tub 10, and a second water supply pipe 14 forsupplying the water from the external water service pipe 2 to a heatingtank 31 included in a steam generator 30. The drum type washing machinealso includes a third water supply pipe 13 for supplying the water fromthe external water service pipe 2 to a rotating drum 11.

Connected to the first water supply pipe 12 are a first water supplyvalve 3 and a detergent storage box 16. The detergent storage box 16 isadapted to store detergent powder therein. The water introduced into thefirst water supply pipe 12 is supplied to the water tub 10 after passingthrough the first water supply valve 3 and detergent storage box 16, sothat it is introduced, along with the detergent, into the water tub 10via an outlet pipe 16 a.

A third water supply valve 5 is installed at the third water supply pipe13 in order to selectively supply water into the rotating drum 11. Aninjection nozzle 13 a is mounted to an end of the third water supplypipe 13 exposed to the interior of the rotating drum 11, in order toinject water into the rotating drum 11.

A drain pipe 17 is arranged beneath the water tub 10 while beingconnected to a bottom of the water tub 10. A pump motor 18 is installedat the drain pipe 17 in order to pump the water and detergent containedin the water tub 10. A drain valve 19 is also installed at the drainpipe 17 downstream from the pump motor 18. A connecting pipe 20 isbranched from the drain pipe 17 between the pump motor 18 and the drainvalve 19. The connecting pipe 20 is connected to the drain pipe 17 atone end thereof while extending to an opening of the rotating drum 11 atthe other end thereof. The connecting pipe 10 has, at an intermediateportion thereof, a diameter larger than that of other portions thereof,to define a cylindrical detergent dissolving chamber 20 b. An injectionnozzle 20 a is provided at the other end of the connecting pipe 20 inorder to inject a detergent solution into the rotating drum 11.

A check valve 21 for prevention of backflow is installed at theconnecting pipe 20. When the drain valve 19 is opened under thecondition in which the check valve 21 is shut off, the water pumped bythe pump motor 18 is externally discharged without flowing backward tothe connecting pipe 20. On the other hand, when the check valve 21 isopened in a closed state of the drain valve 19, the water pumped by thepump motor 18 is introduced into the connecting pipe 20, so that itflows upwardly.

Mounted at one side of the rotating drum 11 is a drum motor 23 which isrotatable in forward and reverse directions. In accordance withoperation of the drum motor 23, the rotating drum 11 rotates in onedirection or rotates in opposite directions in an alternating fashion.

The steam generator 30 is installed at the second water supply pipe 14in order to heat water supplied to the second water supply pipe 14through the second water supply valve 4. As described above, the steamgenerator 30 includes the heating tank 31. Provided in the heating tank31 is a heater adapted to heat water contained in the heating tank 31,and thus, to generate steam, a water level sensor adapted to sense thelevel of water in the heating tank 31, and a water temperature sensoradapted to sense the temperature of water in the heating tank 31. Asteam supply valve 32 is provided at an outlet of the steam generator30.

FIG. 2 is a block diagram illustrating a control configuration appliedto the washing machine according to the illustrated embodiment of thepresent invention.

Referring to FIG. 2, the washing machine includes a controller 60 forcontrolling the overall operation of the washing machine. The controller60 includes a microcomputer 61 and a memory 62. The memory 62 storesinformation about respective wash temperatures and respective wash timescorresponding to various wash courses.

Connected to an input of the microcomputer 61 are an input unit 63 forinputting commands set by the user, a first water level sensor 64 and afirst water temperature sensor 65 respectively installed at desiredpositions in the water tub 10, and adapted to sense the level andtemperature of water contained in the water tub 10, and a second waterlevel sensor 34 and a second water temperature sensor 35 respectivelyinstalled at desired positions in the heating tank 31, and adapted tosense the level and temperature of water contained in the heating tank31.

The washing machine also includes a water supply valve driving unit 66for driving the first through third water supply valves 3 to 5, steamsupply valve 32, drain valve 19, and check valve 21, a motor drivingunit 67 for driving the drum motor 23 and pump motor 18, and a heaterdriving unit 68 for driving the heater 33. These driving units 66 to 68are connected to an output of the microcomputer 61.

The microcomputer 61 controls the overall operation of the washingmachine required to wash laundry by using steam. That is, themicrocomputer 61 controls operations of wetting laundry with a smallamount of water prior to the generation of steam, spraying detergentover the wet laundry, and then injecting steam onto the laundry.

Now, a method for controlling the washing machine having the abovedescribed configuration in accordance with an embodiment of the presentinvention will be described in detail with reference to FIG. 3.

In accordance with the control method, a wash course is first set by theuser under the condition in which laundry has been put into the rotatingdrum 11, and a door of the washing machine has then been closed (Step110). The microcomputer 61 then determines whether or not the set washcourse is a wash course for washing the laundry by using steam (Step120). When it is determined at step 120 that the set wash course is notthe wash course using steam, for example, when the set wash course is awash course for washing the laundry by using cold water and detergent, awash cycle according to the set wash course, that is, the wash courseusing cold water and detergent, is executed (Step 121).

On the other hand, when the set wash course is the wash course usingsteam, the microcomputer 61 controls the valve driving unit 66 to openthe third water supply valve 5. As a result, water from the externalwater service pipe 2 is supplied into the rotating drum 11 through theinjection nozzle 13 a, so that the laundry is wetted by the suppliedwater. In order to uniformly wet the laundry with a small amount ofwater, the microcomputer 61 controls the motor driving unit 67 to rotatethe rotating drum 11 in forward and reverse directions in an alternatingfashion ((a) of FIG. 4A) (Step 130).

The microcomputer 61 then controls the valve driving unit 66 to open thefirst water supply valve 3. As a result, detergent powder is put intothe water tub 10, along with water introduced into the water tub 10 viathe first water supply pipe 12. The microcomputer 61 also controls themotor driving unit 67 to drive the pump motor 18, thereby causing thewater and detergent powder to be fed from the water tub 10 to thedetergent dissolving chamber 20 b. The fed water and detergent powderare mixed in the detergent dissolving chamber 20 b, thereby producing adetergent solution ((b) and (c) of FIG. 4A) (Step 140). In order toachieve a reduction in wash time, steps 130 and 140 may besimultaneously executed.

After the execution of steps 130 and 140, the microcomputer 61 controlsthe motor driving unit 67 to rotate the rotating drum 11 at high speedso that the laundry is in constant contact with an inner peripheralsurface of the rotating drum 11. As a result, an empty space 11 a isdefined at a central interior of the rotating drum 11 ((d) of FIG. 4A)(Step 150).

Subsequently, the microcomputer 61 controls the motor driving unit 67 todrive the pump motor 18, thereby causing the detergent solutioncontained in the detergent dissolving chamber 20 b to be injected intothe rotating drum 11 through the injection nozzle 20 a. Thus, thedetergent solution is sprayed over the laundry ((e) of FIG. 4A) (Step160).

During the spray of the detergent solution over the laundry, themicrocomputer controls the motor driving unit 67 to reduce the rotatingspeed of the rotating drum 11. As the rotating speed of the rotatingdrum 11 is reduced, the laundry, which is in constant contact with theinner peripheral surface of the rotating drum 11, is tumbled. As aresult, the detergent solution can be sprayed over the entire portion ofthe laundry ((f) of FIG. 4A) (Step 170).

After the spray of the detergent solution, the microcomputer 61 controlsthe motor driving unit 67 to rotate the rotating drum 11 in forward andreverse directions in an alternating fashion, in order to transfer thedetergent solution over all portions of the laundry. This operation iscontinued for a predetermined time. In the illustrated embodiment of thepresent invention, the operation is continuously carried out for 5minutes ((g) of FIG. 4B) (Step 180).

Thereafter, in order to store a desired amount of water in the heatingtank 31, the microcomputer 61 controls the valve driving unit 66 to openthe second water supply valve 4. Based on the water level of the heatingtank 31 sensed by the second water level sensor 34, the microcomputer 61subsequently closes the second supply valve 5. The microcomputer 61 alsodrives the heater driving unit 68 to drive the heater 33. In accordancewith operation of the heater 33, the water stored in the heating tank 31is heated. When steam is generated as the water in the heating tank 31is heated, the microcomputer 61 controls the valve driving unit 66 toopen the steam supply valve 32. As a result, the hot steam generated inthe heating tank 31 is injected into the rotating drum 11 through theinjection nozzle 14 a of the second water supply pipe 14. As the waterand air present in the rotating drum 11 are heated by the steam, theinternal temperature of the rotating drum 11 increases rapidly. At thistime, the microcomputer 61 controls the motor driving unit 67 to rotatethe rotating drum 11 in forward and reverse directions in an alternatingfashion. As a result, the laundry is washed in a state in which thesteam injected into the rotating drum 11 comes into contact with thelaundry. In order to perform such a steam wash cycle at a predeterminedwash temperature, the microcomputer 61 controls the steam injection andthe stopping of the steam injection, based on the water temperaturesensed by the first water temperature sensor 65 ((h) of FIG. 4B)(Step190).

During the wash cycle using steam, the microcomputer 61 periodicallydetermines whether or not the wash cycle has been completed (Step 200).When it is determined that the wash cycle has not been completed, themicrocomputer 61 returns its control operation to step 190.

When it is determined at step 200 that the wash cycle has beencompleted, the microcomputer 61 executes rinse and spin-dry cycles (Step210).

As apparent from the above description, in accordance with the presentinvention, steam is injected onto laundry, so as to directly heat thelaundry. Accordingly, the time taken for the laundry to reach a desiredwash temperature is reduced, so that it is possible to achieve areduction in wash time and a reduction in the consumption of electricenergy. In accordance with the present invention, a wash cycle usingsteam is carried out for laundry under the condition in which thelaundry has been wetted with a small amount of water, and then adetergent solution has been uniformly sprayed over the wet laundry.Accordingly, it is possible to achieve a reduction in the amount ofwater to be used and an enhancement in washing while preventing thelaundry from being stained or damaged by hot steam when the steam comesinto contact with the laundry.

Although the exemplary embodiments of the invention have been disclosedfor illustrative purposes, those skilled in the art will appreciate thatvarious modifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the invention as disclosed in theaccompanying claims.

1. A washing machine comprising: a rotating drum for containing laundry;a drum driving unit for driving the rotating drum; a steam generator forgenerating steamand supplying the steam into the rotating drum; and acontroller for controlling operations of injecting the steam suppliedfrom the steam generator into the rotating drum to heat the laundry intoheated laundry, and washing the heated laundry.
 2. The washing machineaccording to claim 1, further comprising: a water supply unit forsupplying water into the rotating drum, wherein the controller drivesthe water supply unit to wet the laundry with water into wet laundrybefore the operation of washing the heated laundry.
 3. The washingmachine according to claim 2, wherein the controller controls the drumdriving unit to rotate the rotating drum in forward and reversedirections in an alternating fashion while the laundry is wetted by thewater.
 4. The washing machine according to claim 2, further comprising:a detergent dissolving unit for supplying a detergent solution into therotating drum, wherein the controller drives the detergent dissolvingunit to spray the detergent solution over the wet laundry.
 5. Thewashing machine according to claim 4, wherein the controller controlsthe drum driving unit to rotate the rotating drum at a predeterminedspeed before the detergent solution is sprayed.
 6. The washing machineaccording to claim 5, wherein the predetermined speed is a speedsufficient to bring the laundry into constant contact with an innerperipheral surface of the rotating drum while defining an empty space ata central interior of the rotating drum.
 7. The washing machineaccording to claim 5, wherein the controller controls the detergentdissolving unit to spray the detergent solution when a rotating speed ofthe drum corresponds to the predetermined speed, and controls the drumdriving unit to reduce the rotating speed of the rotating drum while thedetergent solution is being sprayed.
 8. The washing machine according toclaim 4, wherein the controller controls the drum driving unit to rotatethe rotating drum in forward and reverse directions in an alternatingfashion to transfer the detergent solution sprayed over the laundry oversubstantially all portions of the laundry.
 9. The washing machineaccording to claim 1, wherein the steam generator comprises a heatingtank for containing water, and a heater installed in the heating tankadapted to heat the water in the heating tank, thereby generating steam,the heater being controlled by the controller.
 10. The washing machineaccording to claim 9, wherein the steam generator further comprises awater level sensor for sensing a water level in the steam generator, anda water temperature sensor for sensing a water temperature in the steamgenerator, the water level sensor and water temperature sensorproviding, to the controller, information about the water level andwater temperature sensed thereby.
 11. The washing machine according toclaim 9, wherein the steam generator further comprises a steam supplyvalve installed at an outlet of the heating tank, and the controlleropens the steam supply valve to supply the steam generated from theheating tank.
 12. A control method for a washing machine comprising thesteps of: when a setting of a user corresponds to a wash course forwashing laundry using steam, supplying water into a rotating drum assupplied water, and wetting laundry contained in the rotating drum intowet laundry with the supplied water; spraying a detergent solution overthe wet laundry; generating steam by a steam generator as generatedsteam; injecting the generated steam into the rotating drum, therebyheating the laundry as heated laundry; and washing the heated laundry.13. The control method according to claim 12, wherein the rotating drumis rotated in forward and reverse directions in an alternating fashionwhile the laundry is wetted by the supplied water.
 14. The controlmethod according to claim 12, wherein the rotating drum is rotated at apredetermined speed to define an empty space at a central interior ofthe rotating drum.
 15. The control method according to claim 14, whereinthe detergent solution is sprayed in the empty space defined in therotating drum, and a rotating speed of the rotating drum is reducedbelow the predetermined speed while the detergent solution is beingsprayed in a spray of the detergent solution.
 16. The control methodaccording to claim 15, wherein the rotating drum is rotated in forwardand reverse directions in an alternating fashion for a predeterminedtime after a completion of the spray of the detergent solution.
 17. Thecontrol method according to claim 16, wherein the predetermined timespans from a point of time when the rotating drum is stopped to a pointof time just before the generated steam is injected into the rotatingdrum.